1. Columbia River Basin Water Supply and Demand Forecast for the 2030s Jennifer C. Adam, Assistant Professor Civil and Environmental Engineering Washington State University

2. WSU Modeling Team Civil and Environmental Engineering Jennifer Adam, Assistant Professor Michael Barber, Professor and Director of Washington Water Center Kiran Chinnayakanahalli, Postdoctoral Associate Kirti Rajagopalan, PhD Student Shifa Dinesh, PhD Student Biological Systems Engineering Claudio Stöckle, Professor and Chair Roger Nelson, Research Associate Keyvan Malek, PhD Student School of Economics Michael Brady, Assistant Professor Jon Yoder, Associate Professor Tom Marsh, Professor and Director of IMPACT Center Center for Sustaining Agriculture and Natural Resources Chad Kruger, Director Georgine Yorgey, Research Associate

3. Background  The economic, ecologic, and cultural well being of Washington's Columbia River Basin depends on water  Irrigation largest water user  Economic value of agriculture (5 billion $ in WA)  Water resources sensitive to climate change  Better understanding of future range in supply and demand needed to guide investment decisions

4. Goals  To project 2030s water supply and (agricultural and municipal) demand in the Columbia River Basin  WA Dep. of Ecology Report to State Legislature (November, 2011)

5. Linked WSU Study Components 1. Regional survey of Columbia River Basin water managers 2. Biophysical modeling of historical and future supply and irrigation demand 3. Economic analyses of domestic and international factors driving agricultural production 4. Municipal demand forecast 5. Hydropower review

6. Modeling Integration: *Surface Hydrology *Cropping Systems *Water Management *Economics Modeling Approach

7. http://www.hydro.washington.edu/2860/Slide courtesy of Alan Hamlet The UW CIG Supply Forecast

8. Application of the UW CIG Water Supply Forecast  WSU is building directly off of the UW water supply forecasting effort (Elsner et al. 2010) by starting with these tools that were developed by UW Climate Impacts Group:  Implementation of the VIC hydrology model over the Pacific Northwest at 1/16 th degree resolution  Reservoir Model, ColSim  Historical climate data at 1/16 th degree resolution  Downscaled future climate data at 1/16 th degree resolution  WSU added elements for handling agriculture:  integrated crop systems and hydrology  irrigation withdrawals from reservoirs, and including some smaller reservoirs, curtailment modeling  economic modeling of farmer response

9. Models Used VIC Hydrology Liang et al, 1994 CropSyst Cropping Systems Stockle and Nelson 1994

10. Overview of Framework

11. VIC-CropSyst Model 1. Weather (D) 2. Soil Soil layer depths Soil water content 3. Water flux (D) Infiltrated water 4. Crop type Irrigation water = Crop Water Demand /irrigation efficiency Sow date Crop interception capacity Crop phenology Crop uptake (D) Water stress (D) Current biomass (D) Crop Water demand (D) Harvest day Crop Yield VICCropSyst D – communicated daily

12. T – Transpiration I P – Interception capacity I – Infiltration Ir – irrigation Wd- Water demand Q – Runoff Q 01 – Drainage from 0 to 1 Q 02 – Drainage from 0 to 2 Q b – Baseflow W 0 – water content in 0 W 1 – water content in 1 W 2 - water content in 2 Tmin, Tmax – daily minimum and maximum temperature Ws – wind speed RH – Relative humidity SR – Solar radiation QbQb Q 12 T IPIP Redistribute I, W 0, W 1 and W 2 to CropSyst layers Q Q 01 W 0,W 1, W 2 T 0, T 1, T 2, I P, Wd I CropSyst VIC Ir Daily Tmin, Tmax, Ws, RH, SR, I VIC-CropSyst : Coupling Approach

13. Invoking CropSyst within VIC gridcell Crop 1 VIC grid cell (resolution=1/16°) (~ 33 km 2 ) Crop 2 Non-Crop Vegetation CropSyst is invoked

14. Crops Modeled  Winter Wheat  Spring Wheat  Alfalfa  Barley  Potato  Corn  Corn, Sweet  Pasture  Apple  Cherry  Lentil  Mint  Hops  Grape, Juice  Grape, Wine  Pea, Green  Pea, Dry  Sugarbeet  Canola  Onions  Asparagus  Carrots  Squash  Garlic  Spinach Generic Vegetables  Grape, Juice  Grass hay  Bluegrass  Hay  Rye grass  Oats  Bean, green  Rye  Barley  Bean, dry  Bean, green Other Pastures Lentil/Wheat type  Caneberry  Blueberry  Cranberry  Pear  Peaches Berries Other Tree fruits Major Crops

15. Physical System of Dams and Reservoirs Reservoir Operating Policies Reservoir Storage Regulated Streamflow Flood Control Energy Production Irrigation Consumption Streamflow Augmentation VIC Streamflow Time Series The Reservoir Model (ColSim) (Hamlet et al., 1999) Slide courtesy of Alan Hamlet

16. ColSim Reservoir Model (Hamlet et al., 1999) for Columbia Mainstem Model used as is, except for  Withdrawals being based on VIC-CropSyst results  Curtailment decision is made part of the reservoir model Green triangles show the dam locations

17. Curtailment Rules (Washington State) Curtailment based on instream flow targets  Columbia Mainstem  Lower Snake  Central Region (Methow, Okanogan, Wenatchee)  Eastern Region (Walla Walla, Little Spokane, Colville) Prorated based on a calculation of Total Water Supply Available  Yakima

18. Yakima Reservoir Model Irrigation demand from VIC/CropSyst Curtailment rules Proratable water rights prorated according to Total Water Supply Available (TWSA) calculated each month Monthly Inflows from VIC-CropSyst Total System of Reservoirs (capacity 1MAF approx.) Objectives : Reservoir refill by June 1 st Flood space availability Instream flow targets Gauge at Parker

19. Model Calibration/Evaluation  Calibration:  Streamflows (we used calibration from Elsner et al. 2010 and Maurer et al. 2002)  Crop Yields (using USDA NASS values)  Irrigation Rules (using reported irrigated extent by watershed)  Evaluation:  Streamflows (Elsner et al. 2010 and Maurer et al. 2002)  USBR Diversions from Bank’s Lake (for Columbia Basin Project)

20. Biophysical Modeling: VIC-CropSyst, Reservoirs, Curtailment Crop Yield (as impacted by climate and water availability) Adjusted Crop Acreage Selective Deficit Irrigation 1.Water Supply 2.Irrigation Water Demand 3.Unmet Irrigation Water Demand 4.Effects on Crop Yield Economic Modeling: Agricultural Producer Response Water Management Scenario Future Climate Scenario Inputs Modeling StepsOutputs Integration with Economics Economic Scenario

21. Model Scenarios: Low, Middle, High  Climate Change Scenarios  HADCM_B1, CCSM_B1, CGCM_B1, PCM_A1B, IPSL_A1B  Hybrid Delta Downscaling Approach (2030s climate) (UW CIG)  GCMs and Emission Scenarios chosen for low/middle/high precipitation and temperature change combinations  Water Management Scenarios  Additional Storage Capacity  Cost Recovery for Newly Developed Water Supply  Economic Scenarios  International Trade  Economic Growth

22. 1. Columbia Basin-Scale and Columbia Mainstem 2. Example Watershed-Scale 1. Yakima 2. Walla Walla Results

23. Water Supply Entering Washington Eastern: increasing Western: decreasing Top: 2030 Flow (cfs) Bottom: Historical Flow (cfs)

24. Water Supply Entering Columbia Mainstem Eastern: increasing Western: decreasing Top: 2030 Flow (cfs) Bottom: Historical Flow (cfs)

25. Snake River and Columbia River Supplies Snake RiverColumbia River

26. Regulated Supply vs Demand for Columbia River Basin (at Bonneville) 2030 results are for - HADCM_B1 climate scenario - average economic growth and trade Note: Supply is reported prior to accounting for demands

27. Regulated Supply and In-Stream Flow Requirements at Key Locations Future (2030) Historical (1977-2006) Note: Supply is reported prior to accounting for demands

28. Watersheds Included in Study

29. Out-of-Stream Demand by Watershed

30. Yakima

31. Yakima Supply

32. Yakima Demand

33. Yakima Supply and Demand Historical Hadcm_B1

34. Walla

35. Walla Walla Supply

36. Walla Walla Demand

37. Walla Walla Supply and Demand Historical Hadcm_B1

38. Conclusions and Future Directions  Changes in supply (average of all climate scenarios)  3% increase in annual flow at Bonneville  However, 16% decrease in summer flow at Bonneville  Changes in demand (middle econ and climate scenarios)  10% increase in agricultural demand over basin  12% increase in agricultural demand over state  Some watersheds more impacted than others  Increased irrigation demand, coupled with decreased seasonal supply poses difficult water resources management questions, especially in the context of competing in stream and out of stream users of water supply.

40. Time Line on Report to State Legislature  Outreach workshops in Spokane, Wenatchee, and Tri-Cities (last month)  Draft Legislative Report has been released:  http://www.ecy.wa.gov/programs/wr/cwp/wsu_supply- demand.html http://www.ecy.wa.gov/programs/wr/cwp/wsu_supply- demand.html  Final Legislature Report by end of October:  Responses to comments from workshops  High/low economic scenarios  Unmet demand due to curtailment  Full Technical Report by end of year:  Impacts of climate change and curtailment on crop yield  Full economic scenarios

41. Longer-Term Directions  2016 Report to State Legislature, improvements that are being considered  Groundwater dynamics  Columbia-basin scale economics (not just state-level)  Fuller inclusion of climate change scenarios  More ground-truthing

42. BioEarth http://www.cereo.wsu.edu/bioearth/ Overarching Goal: To improve the understanding of regional and decadal- scale C:N:H 2 O interactions in context of global change to better inform decision makers involved in natural and agricultural resource management.

43. Acknowledgements  Alan Hamlet and others at UW CIG  Peer reviewers Bob Mahler, Ari Michelson, Jeff Peterson  Dana Pride  WA Dep. of Ecology

44. THANK YOU!

45. Uncertainties 1-Future climate (due to GCMs, greenhouse emission scenarios and downscaling approach) 2-Model structure (VIC-CropSyst) 3-Water management and economic scenarios 4-Cropping pattern - discrepancy between multiple data sources 5-Irrigation supply – poor data on groundwater and surface water proportions of the supply 6-Irrigation methods a)No information for upstream states b)Conveyance loss is not modeled (This is a proportion of the demand at each WRIA)

46. Change in Crop Yield Crop type Percent change (tons/hectare) Corn -12.9 Spring Wheat 7.7 Winter Wheat 25.1 Alfalfa 10.0 Apples 0.0 Cherry Orchard 0.0 Potatoes -9.1 Grapes 0.0 - Change in some crop yield - Trees does not show significant change - Results are for full irrigation

47. Crop Mix Information for the Columbia River Basin  United States Department of Agriculture (USDA)  Washington State Department of Agriculture (WSDA)

49. Example WRIA Results: – Supply in WENATCHEE

50. Example WRIA Results - Demand in WENATCHEE

51. Example WRIA Results – Supply and Demand in WENATCHEE